Field of the Invention
The present invention relates to an apparatus body of an image pickup apparatus like a digital camera to which an interchangeable lens is detachably attached through a lens adapter having an electrical communication unit, and to the lens adapter for equipping the interchangeable lens to the apparatus body.
Description of the Related Art
When a lens mount of an interchangeable lens has a different shape from a lens mount of a camera body of a lens interchangeable camera, the interchangeable lens is detachably attached to the camera body through a lens adapter. Moreover, some lens adapters have an electrical communication unit in order to enable communication between an interchangeable lens and a camera body.
Since a lens adapter having an electrical communication unit has many contact members that electrically connect the electrical communication unit and a camera body, reliability of the electric connection of the contact members of the lens adapter with the contact members of the camera body and durability of contact parts are needed.
Consequently, there is a proposed technique that constitutes both of the contact members of the lens adapter and the contact members of the camera body as a plurality of movable contact pins that are movably supported in an optical axis direction and are energized so that the pins are mutually contact to each other (Japanese Laid-Open Patent Publication (Kokai) No. H7-84307 (JP H7-84307A)).
However, the configuration of the above-mentioned publication changes the contact positions between the contact pins of the lens adapter and the contact pins of the camera body when a spacer is inserted into a space between the lens adapter and the camera body in order to finely adjust a flange back (a distance from the lens adapter to an image pickup device). Accordingly, there is a possibility that contact pressure between the contact pins of the lens adapter and the contact pins of the camera body varies, which deteriorates the reliability of electric connection.
On the other hand, there is a proposed lens adapter that is attached to a lens mount of a camera body so as to cover a collapsible lens barrel as a dustproof lens adapter for attaching a wide converter as an interchangeable lens (Japanese Laid-Open Patent Publication (Kokai) No. 2010-72225 (JP 2010-72225A)).
When an interchangeable lens is attached to a camera body through a lens adapter, a dustproof measure that prevents invasion of foreign substances through a gap between the lens adapter and the camera body will be needed. When there is a gap between a lens adapter and a camera body, foreign substances, such as dust, may be invaded on an optical path of an interchangeable lens and is taken in an image, which deteriorates image quality.
On the other hand, when a lens adapter has an electrical communication unit that enables communication between an interchangeable lens and a camera body, it is difficult to seal the electrical communication unit of an uneven shape by a dustproof member. In particular, when the interchangeable lens is attached to the camera body by a rotary operation of the lens adapter, the dustproof measure of the electrical communication unit becomes more difficult.
However, JP 2010-72225A does not disclose any dustproof measure between a lens adapter that has an electrical communication unit and a camera body. Moreover, since an air hole is formed on an exterior of the camera body in order to avoid an adverse influence on a collapsing operation by pressure variation in a space between the camera body and the lens adapter when the lens barrel is collapsed, dust etc. may invade inside of the camera body through the air hole.